Help with jumping

[shadycharacter]

With the code I'm using right now, jumping is very choppy, and really doesn't look at all like jumping. I'm going for more of a "super mario" type jump, how can I achieve this? Here is my current code for movement and jumping

public void keyReleased(KeyEvent k) {
		  	  int keyCode = k.getKeyCode();
		  switch (keyCode) {
			  case KeyEvent.VK_SPACE:
			  y += 60;
			  	break;

			}
		  }
	    public void keyTyped(KeyEvent k) { }
	    public void keyPressed(KeyEvent k) {
		  	  int keyCode = k.getKeyCode();

	        switch (keyCode) {

	        case KeyEvent.VK_A:
	        x -= 10;
	        imagename1 = "boxleft.png";
	        box1.load(imagename1);
	        	break;

	        case KeyEvent.VK_D:
	        x += 10;
	        imagename1 = "boxright.png";
	        box1.load(imagename1);
	        	break;

	        case KeyEvent.VK_SPACE:
	        y -= 60;
	        if (imagename1 == "boxright.png")
						  x += 50;
			else
			  x -= 50;
	        	break;
			}

[shadycharacter]

Also another problem I just discovered. If you hold in spacebar the character continues to fly up